FFLD Coils

Coils are basic graphic elements of the FFLD language. A coil is associated with a Boolean variable which is displayed above the graphic symbol. A coil performs a change of the associated variable according to the flow on its left-hand side.

Below are the six possible coil symbols:

Coils Description
boolVariable

   -( )-
Normal: the associated variable is forced to the value of the flow on the left of the coil.
boolVariable

   -(/)-
Negated: the associated variable is forced to the negation of the flow on the left of the coil.
boolVariable

   -(S)-

Set: the associated variable is forced to TRUE if the flow on the left is TRUE. (no action if the flow is FALSE)

boolVariable

   -(R)-

Reset: the associated variable is forced to FALSE if the flow on the left is TRUE. (no action if the rung state is FALSE)

boolVariable

   -(P)-
Positive transition: the associated variable is forced to TRUE if the flow on the left changes from FALSE to TRUE(and forced to FALSE in all other cases)
boolVariable

   -(N)-
Negative transition: the associated variable is forced to TRUE if the flow on the left changes from TRUE to FALSE(and forced to FALSE in all other cases)

  • When a contact or coil is selected, you can press the Spacebar to change its type (normal, negated...).

    When your application is running, you can select a contact and press the Spacebar to swap its value between TRUE and FALSE.



  • Although coils are commonly put at the end, the rung can be continued after a coil. The flow is never changed by a coil symbol.